The present invention relates to a canister used for an evaporated fuel processing device of an automobile.
Conventionally, in a canister made of resin which contains an absorbent of evaporated fuel which is composed of activated carbon, as shown in FIG. 7C, a peripheral wall 1 is integrally formed with a top wall 2, and a bottom cover 3 is fixed on a lower portion of the peripheral wall 1 by friction welding, spin welding or the like, thereby constituting a casing of the canister. (For example, Japanese Utility Model Unexamined Publication No. 60-159873.)
In this manner, the bottom cover 3 is securely welded on the lower end surface of the peripheral wall 1 which forms the casing, and consequently, welded portions 4 are located at lower portions of the casing for the following reason.
For example, as shown in FIG. 8, a peripheral wall 1 of a casing is integrally formed with a bottom wall 3, and after filling an absorbent 5 in the casing opened at the top, a top cover 6 is attached to the casing, so that welded portions can be located at upper portions of the casing. However, it is difficult to penetrate a supplying conduit 7 through layers of the absorbent 5 filled in the casing.
Therefore, a casing integrally formed with a top wall 2 and opened at the bottom is turned upside down, as shown in FIG. 7A, to have a posture vertically reverse to a posture for use, and a supplying conduit 7 provided on the top wall 2 is extended upright in the casing. An absorbent 5 is filled in the casing from a top opening 1a, and a bottom cover 3 is thereafter welded securely on the casing, as shown in FIG. 7B. Then, the casing is turned upside down to have the posture for use, as shown in FIG. 7C.
As a result, welded portions 4 are located at lower portions of the casing in the posture for use.
With the casing including the bottom cover 3 welded thereon and the welded portions 4 located at the lower portions of the casing, as described above, the welded portions 4 having the lowest strength are sometimes separated at the time of a collision of the automobile, so that the bottom cover 3 will be opened or come off, and that all the absorbent 5 will drop out of the casing.
In such a case, if the absorbent 5 scatters in an engine room, various problems arise because evaporated fuel is absorbed in the absorbent 5.